4/14/09: Columbine

Salt Lake City, UT – Next week marks the 10th anniversary of the tragedy at Columbine High School in Colorado. Two students set out to "leave a lasting impression on the world," and their shooting spree left 23 wounded and 15 dead. Despite the theories that soon followed, journalist Dave Cullen says that 18-year-old Eric Harris and 17-year-old Dylan Klebold had lived fairly normal lives. Cullen has written a new book, and Tuesday, he joins Doug to explain the psychological journey of the boys who became killers.